【摘要】 在兰州市设置11个采样点,于夏季和冬季分别采集大气降尘,研究了兰州市大气降尘中重金属元素的污染特征及其对土壤中重金属积累的影响,分析降尘中Cu、Pb、Mn、Cr、Cd、Ni和Zn质量分数.结果表明兰州市大气降尘中重金属质量分数为Mn>Zn>Pb>Cr>Cu>Ni>Cd.夏季平均质量分数依次为640.37、368.34、131.36、98.11、68.72、38.23、2.73 mg/kg;冬季平均质量分数依次为497.31、380.00、111.62、1 01.30、101.28、46.99、4.82 mg/kg,除Pb和Mn外,其余金属质量分数均在冬季高于夏季,各元素在冬季富集因子均高于夏季.Mn的富集因子接近1,Pb、Ni、Zn、Cu和Cr的富集因子大致在1~10,均不同程度的受到人类活动影响,而Cd的富集因子大于10,主要来源于人类活动.主成分分析表明,Cr、Ni和Zn与工业排放的烟尘有关,Fe、Mn与降尘的自然来源有关,Pb、Cu元素与交通污染及煤炭燃烧排放有关.更多还原

【Abstract】 Heavy metals in the atmospheric dustfall can be a cause for contamination and lead to the heavy metal accumulation in the soil.In order to learn about their polluting characteristics and their effects in Lanzhou,China,samples of atmospheric dustfall were collected from 11 sampling sites respectively in summer and winter.All dustfall samples were analyzed for the concentrations of Cu,Pb,Mn,Cr,Cd,Ni and Zn.And the source and the accumulation level of the atmospheric dustfall were also researched into.Theresults demonstrated that the order of the concentrations of the heavy metal elements was Mn>Zn>Pb>Cr>Cu>Ni>Cd.The average concentrations of summer were 640.37,368.34,131.36,98.11,68.72,38.23 and 2.73 mg/kg and those of winter were 497.31,380.00,111.62,101.30,101.28,46.99 and 4.82 mg/kg,with those in winter being higher than in summer,except for Pb and Mn.Fe was selected as the reference element to calculate the heavy metal enrichment factor,which indicated that each of the elements’ enrichment factor(EF) was higher in winter than in summer.According to the results the EF score of Mn was close to 1,while the EF scores of Pb,Ni,Zn,Cu and Cr were more higher,which were effected by human activities at different levels.But among them,the EF of Cd presented a high level that was mainly due to the human activity.A principal component analysis was performed and three main sources were identified:Cr,Ni and Zn were correlated to industrial emission;Fe and Mn were derived from soil particles(natural sources);Pb,Cu had a connection with coal combustion and traffic exhaust.更多还原